Lifetime and droplets size distribution of dense sprays
Phys. Rev. Fluids 11, 064501 – Published 1 June, 2026
DOI: https://doi.org/10.1103/ms1r-7jb9
Abstract
We study the evaporation dynamics of spray lamellae—the paradigm of dense sprays evaporation—injected into a quiescent dry environment from an oscillating source. Lamellae are made of a collection of densely packed microns in size droplets of liquids with different volatilities, initially in equilibrium with their vapor. Building on an earlier study [de Rivas et al., Phys. Rev. Fluids 1, 014201 (2016)], we confirm that the lifetime of an individual droplet embedded in such a spray is much larger than expected from the usual d-squared law describing the fate of a single isolated droplet evaporating in a quiescent environment. By analogy with the way mixing times of scalars are understood from the coupling between stretching and diffusion, we show that the boundary between the spray and the diluting environment is slaved to the dynamics of its saturating vapor concentration field as envisaged in Villermaux et al. [Phys. Rev. Fluids 2, 074501 (2017)], thus explaining the very substantial evaporation delay of the liquid phase in spite of its division into fine droplets. We quantify the evaporation time for the stirring protocol of an undulating lamellae as well as, thanks to unique in situ measurements, the concomitant evolution of the droplets number, and size distribution in the spray.
